1. Where does all that glucose come from?
Chapter 3
Photosynthesis
Where does all that glucose come from?

2. How does it do that?

3. What is it?
radiant energy
Photosynthesis uses radiant energy from the sun to fix carbon dioxide into carbohydrates
The captured radiant energy is stored within the bonds of the carbohydrate as chemical energy
Photosynthesis
CO2
glucose
CO2
CO2
CO2
CO2
CO2

4. Photosynthesis is used by many autotrophs to make their own food
egs. vascular plants, algae, cyanobacteria

5. That’s a lot of photosynthesis

6. http://www. smhi. se/weather/baws_ext/info/2004/Baltic_algae_2004_en

7. Overall (Net) Equation
Photosynthesis
CO2
H2O H+
Energy O2
glucose
CO2 + H2O + energy  glucose + O2

8. Overall (Net) Equation
Cellular Respiration
Photosynthesis
CO2
H2O H+
Energy O2
glucose
glucose + O2  CO2 + H2O + energy
Photosynthesis and Cellular Respiration appear to be reverse processes, but they use very different mechanisms

9. Similarities
Both cellular respiration and Photosynthesis are similar in that both use:
electron transport chains
dissolved enzymes
membrane-enclosed space for chemiosmosis

10. Plant Tissues Plants are made of various types of tissues
egs. Stem, leaves, roots, reproductive organs
The main site of photosynthesis is the leaves, although chloroplasts are found in all green plant parts

11. Leaves Mesophyll Vascular Bundles Epidermis cuticle epidermis
stomate
palisade mesophyll
spongy mesophyll
vascular bundle

12. Leaves Leaves have 3 main types of tissues: Epidermis
vascular bundle
palisade mesophyll
cuticle
spongy mesophyll
stomate
Leaves have 3 main types of tissues:
Epidermis
Usually one cell thick and secrets a waxy cuticle to prevent water loss
Pores called stomata found in lower epidermis

13. Leaves Mesophyll Most photosynthesis occurs here
epidermis
vascular bundle
palisade mesophyll
cuticle
spongy mesophyll
stomate
Mesophyll
Most photosynthesis occurs here
Two layers of parenchyma cells
Palisade layer
Cell arrangement maximizes exposure to light
Spongy layer
Loose arrangement of cells leaving air spaces for gas exchange

14. Leaves Vascular Bundles Transport system of the plants
epidermis
vascular bundle
palisade mesophyll
cuticle
spongy mesophyll
stomate
Vascular Bundles
Transport system of the plants
Contains xylem (water transport) and phloem (sugar transport)

15. Opening/Closing Stomata
The guard cells (stomata) can be opened and closed to regulate gas exchange and minimize water loss in leaves
Pore
Chloroplast
OPEN
CLOSED
Guard Cells

16. Cell is now hypertonic to surroundings
Opening Stomata
Cell is now hypertonic to surroundings K+
H2O H+
To open the stomata:
Potassium ions (K+) are actively pumped into the guard cells (uses ATP)
This causes the GCs to become hypertonic to their surroundings
Water is drawn into the GCs, increasing turgor pressure K+
ATP K+ K+ K+ K+
CLOSED
OPEN

17. OPEN Closing Stomata To close the stomata:
K+ pumps deactivated allowing ions to diffuse out
Water drawn back out of the GC with the K+ ions
Decrease in turgor pressure makes GCs go limp (flacid)
ATP K+ K+ K+ K+ K+ K+
OPEN

18. Cell is now hypotonic to surroundings
Closing Stomata
Cell is now hypotonic to surroundings
H2O H+
To close the stomata:
K+ pumps deactivated allowing ions to diffuse out
Water drawn back out of the GC with the K+ ions
Decrease in turgor pressure makes GCs go limp (flacid) K+ K+ K+ K+ K+ K+
OPEN

19. CLOSED OPEN Closing Stomata To close the stomata:
H2O H+
To close the stomata:
K+ pumps deactivated allowing ions to diffuse out
Water drawn back out of the GC with the K+ ions
Decrease in turgor pressure makes GCs go limp (flacid)
CLOSED
OPEN